From 235c614e68eb2085d97f0afa2b1bd8ee45a4eb37 Mon Sep 17 00:00:00 2001
From: Clyde Stubbs <2366188+clydebarrow@users.noreply.github.com>
Date: Thu, 15 Oct 2026 21:55:19 +1100
Subject: [PATCH] [epaper_spi] Ensure test card gets drawn (#20804)

---
 esphome/components/epaper_spi/display.py      |  1 +
 .../config/test_card_update_interval.yaml     | 22 +++++++++++++++++++
 tests/component_tests/epaper_spi/test_init.py | 12 ++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 tests/component_tests/epaper_spi/config/test_card_update_interval.yaml

diff --git a/esphome/components/epaper_spi/display.py b/esphome/components/epaper_spi/display.py
index 487e8e5ef40..32ac0b9da70 100644
--- a/esphome/components/epaper_spi/display.py
+++ b/esphome/components/epaper_spi/display.py
@@ -208,6 +208,7 @@ def _final_validate(config) -> None:
         else:
             # If no drawing methods are configured, and LVGL is not enabled, show a test card
             config[CONF_SHOW_TEST_CARD] = True
+            config[CONF_UPDATE_INTERVAL] = update_interval("1min")
     elif CONF_UPDATE_INTERVAL not in config:
         config[CONF_UPDATE_INTERVAL] = update_interval("1min")
 
diff --git a/tests/component_tests/epaper_spi/config/test_card_update_interval.yaml b/tests/component_tests/epaper_spi/config/test_card_update_interval.yaml
new file mode 100644
index 00000000000..fb6eeec8d77
--- /dev/null
+++ b/tests/component_tests/epaper_spi/config/test_card_update_interval.yaml
@@ -0,0 +1,22 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+
+spi:
+  clk_pin: GPIO18
+  mosi_pin: GPIO19
+
+display:
+  - platform: epaper_spi
+    id: epaper_display
+    model: ssd1677
+    dc_pin: GPIO21
+    busy_pin: GPIO22
+    reset_pin: GPIO23
+    cs_pin: GPIO5
+    update_interval: never
+    dimensions:
+      width: 200
+      height: 200
diff --git a/tests/component_tests/epaper_spi/test_init.py b/tests/component_tests/epaper_spi/test_init.py
index 4b8f5788925..81e197abf81 100644
--- a/tests/component_tests/epaper_spi/test_init.py
+++ b/tests/component_tests/epaper_spi/test_init.py
@@ -580,3 +580,15 @@ def test_model_with_no_default_init_sequence_generates(
     # init_sequence_length, ...); a length of 0 confirms the empty init
     # sequence array was generated instead of raising during code generation.
     assert re.search(r"epaper_spi::EPaperT133A01\([^;]*,\s*\w+,\s*0\);", main_cpp)
+
+
+def test_test_card_overrides_update_interval(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    """With nothing else to draw, update_interval is not left at never for the test card."""
+    main_cpp = generate_main(component_config_path("test_card_update_interval.yaml"))
+
+    match = re.search(r"epaper_display->set_update_interval\((\d+)\);", main_cpp)
+    assert match is not None
+    assert int(match.group(1)) != 4294967295